The Beast Within
by rlu1
Summary: After finding grey strands on his head, Moriarty sets about crafting an heir. In the meantime, the once unsentimental Sherlock has fallen in love with his flatmate, and has grown very protective of him. What will happen when Moriarty's "fun and games" threaten John? Johnlock. AU in which Khan (Star Trek: Into Darkness), Moriarty and Sherlock share DNA and the result is dynamite!
1. The Heir and His Archenemy

_**Welcome to The Beast Within (formerly entitled The Heir and His Archenemy)!**_

_**This is a crossover of Sherlock and Star Trek: Into Darkness in which we witness the explosive chemistry that occurs when Khan, Moriarty, and Sherlock's DNA mixes together. I do not own either the Sherlock or Star Trek: Into Darkness worlds, and this fanfic is only for entertainment purposes. **_

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Jim Moriarty stared into the mirror and sighed, lower lip quivering slightly as he pulled at the patch of greying hair sitting atop his head. But then his pout transformed into a mischievous grin, and soon the room filled with laughter - maniacal, wild, wicked, and bubbling.

Oh, he was a genius. Utterly brilliant. And this was so, so much fun.

He had realized it about a year ago: the horrifying fact that he was getting older. And despite his massive intellect, his incredible mind, and his powerfully conniving thoughts, he could not save himself from the inevitable darkness of exhaustion which eventually led to death. The need for food, for drink, for sleep - these weaknesses of the body laughed at the ironic powerfulness and powerlessness of his mind, so brilliant and yet so unable to overcome life's basic necessities. Eventually, his body would deteriorate beyond repair and turn to ashes and dust. He thought of the colourlessness of a world without his fire, his spark, his scathing burn. Such a world should not exist and, so, he had devised a plan to ensure that it never would.

It had started with one body, injected with a mixture of his DNA and genes from powerful creatures - the anaconda, the grizzly bear, the gorilla, the bald eagle. His heir was crafted to be genetically superior to any living creature on this earth. Because intellect alone was entertaining, but intellect laced with uncivilized, unbridled strength was much more fun and much more destructive. And then he had inserted into the body the genes of some of the world's finest regenerators - lizards, spiders, starfish - in a desperate attempt to prevent his heir from meeting the hopeless and permanent fate of bodily weakness and death.

The result? A superhuman, better in every single way than the average person. Smarter, stronger, wilder, hungrier, faster, and virtually unbreakable.

He lovingly placed the body in a metal tube. A tube in which the creature could sleep peacefully until the time came - the _right_ time. A wave of pride washed over Moriarty as he stared down at his slumbering creation. The body looked just like his, slender in form, about 5 foot 7 in height, head covered in short dark hair, forehead large and full, mouth resting in a twisted grin. But as Moriarty watched his sleeping heir, he realized the dullness of it all; of a world where there was only one genius, only one havoc maker. A world in which his heir would have no one brilliant enough to join in the fun and games. Every good fairy tale needed a hero and a villain, someone on the side of the angels and someone on the side of the devil - otherwise there were no mazes to be followed, no tricks to be unraveled, no puzzle pieces to fit together or tear apart, no souls to be manipulated, no hearts to burn. Boring, boring, boring. Moriarty knew right then that he needed the DNA of the world's only consulting detective, Sherlock Holmes.

Moriarty had enticed that brilliant curly head out of 221B by kidnapping a helpless young girl in the dark of night, strapping a bomb to her, hiding her in the attic of an old, abandoned house on the outskirts of town, and sending the detective a blurry picture of the mystery location with the message that there were two hours to solve the puzzle or else the pretty little lass would be blown to smithereens. Of course, the madman's plan had worked perfectly. Sherlock had rushed out of the flat, long legs and excited eyes, with ever-loyal John close behind. So predictable. So innocently predictable. It had provided the perfect amount of time for Moriarty to enter the flat and steal one solitary little cup, sitting wistfully in the sink waiting to be washed. Obviously Sherlock's cup and not John's because of the distinct smell of coffee mixed with sugar. Anyone who spent enough time observing the two men knew that Sherlock took his coffee black with two sugars, while John took his coffee with no sugar. And so, with this cup, Moriarty pulled Sherlock's DNA and injected it into a second body to create the arch enemy of his heir.

As the days went on and the DNA coursed throughout the second body, it took on an appearance that was rather akin to the consulting detective's. Angular face, lanky limbs, long legs, slender torso, about 6 feet in height - and though the hair did not fall around the face in curls, it was the same dark chocolate shade as Sherlock's. But Moriarty was displeased. The face that slept before him was emotionless, lips and eyebrows forming a straight, unreadable line. At this discovery, Moriarty gritted his teeth - but then his eyes lit up wickedly and another bubbling laugh erupted from his stomach. He quickly grabbed a syringe and extracted blood from his arm, sighing ecstatically as he watched the deep red flow out of him. Then, with a sharp turn, he injected the body with the warm red liquid which contained those elements that were missing in Sherlock: cruelty and savagery.

The detective had many frustrating traits. For starters, he lacked any social skills, cared nothing for sentiment, and didn't feel emotional attachment towards others. But he was certainly not cruel and, perhaps because of his lack of affectionate feelings, he had never been moved to act ferociously. Savagery was so often saved for those who had been left betrayed or heart-broken, and who needed to make someone feel their unbearable hurt. Moriarty knew this hurt well, could still remember the late night when a solitary bullet had pounded through the heart of the only woman he had ever truly loved. But the detective would not know the feeling of the finer emotions if they ran him over in the form of a freight train. And so Moriarty wrung his hands in excitement as he thought of the sizzling combination of consulting criminal and consulting detective crashing together in one big, beautiful, cacophonous symphony within the veins of the sleeping body below him.

His work was finally done. With a sigh of contentment, he shut off the lights and gently began to sing, a lonely, haunting sound. The soft, rich tones of "Stayin' Alive" soon filled every corner of the room, seeping into the walls and drowning the darkness. And then, the madman was gone and the room embraced the utterly untouchable silence.

Little did Moriarty know that it would be a long 300 years before the slumbering bodies were discovered. And the consulting criminal would surely scream in agony from the depths of hell if he were to realize that only one of the creatures he so carefully crafted was roused from sleep: the one who rose about 6 feet in height, slender but solid, with eyes that pierced as blue as jagged ice...an extraordinary, brilliant, hungry superpower trapped all alone in an agonizingly average world. How hopelessly, _hopelessly_ dull. Stayin' alive indeed.


	2. The Finer Passions

_**Thanks so much to those of you who have reviewed and favourited this story so far. Your support is my motivation. :)**_

_**I know that I had originally said this would be a one-shot, but it appears that the writing bug has infected me and I can't stop writing! I had all sorts of ideas come to me last night so, as a result, this will indeed end up being a multiple chapter fic.**_

_**Onto chapter 2...**_

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Moriarty was a smart man and he was right about many things. But Sherlock Holmes was a smarter man still and Moriarty was certainly incorrect about him. Contrary to Moriarty's beliefs, Sherlock was personally familiar with the finer passions, though he had only ever felt them for one person. This one person was former army doctor, Dr. John Watson - the most adorable, handsome, darling, sweet, huggable enigma of all time, and the flatmate, friend, and work partner of the world's only consulting detective. Loyal, steady John had entered Sherlock's life with the strength of ten thousand freight trains and Sherlock had known that he would not be able to fight against John's mesmerizing power.

Yes, John was an enigma and Sherlock enjoyed every single second spent trying to crack the doctor's code. Most people were black and white - they either liked routine or longed for spontaneity, desired to travel or were homing pigeons, enjoyed the morning or embraced the night. Not John. John was anything but black and white. John was a dazzling, marvellous, extraordinary shade of grey with all sorts of spaces that needed to be filled in and explored. John thirsted for danger and yet appreciated peaceful nights in front of the telly. He was tender and gentle, yet oh so good with a gun. He wore ugly jumpers in dull colours but somehow was the most gorgeous man in the world with those bright eyes and delicate lips. Oh goodness, Sherlock wanted to explore every single part of John and then discover the parts that the doctor didn't even know existed.

Before John, the Work was the only activity that provided the detective's constantly turning mind any kind of peace and, thus, the Work was the only thing that Sherlock saw as giving his life value. But then John came along and suddenly _everything_ provided Sherlock's life with meaning. Because everything screamed John - the Work, the flat, the streets of London.

The essence of John was everywhere but, most of all, it was in Sherlock's bed - for it was in this bed that Sherlock had explored John so fully that suddenly life was more than just about the Work…more than the tumbling turning cacophony of Sherlock's mind…no…because for once his mind was slowing into a gentle, soothing, numbingly pleasant liquid, thick and sweet as honey…suddenly his mind wasn't filled with the agitating, annoying noise that had become so familiar to him…suddenly everything was quiet and clear. And in that moment, Sherlock could not understand why he had scoffed at sentimental emotions for so long…because if passion made him see everything _this_ clearly, then it would surely serve to be the most valuable, useful, helpful tool to the Work yet. And with this quick observation of the value of the finer passions, Sherlock let himself go and fell in love with John right there in bed.

It happened thus. They had just come home from a particularly exhilarating case in which they had chased a murderer through the hustle and bustle of London Underground. This particular murderer had been shoving unsuspecting strangers to their deaths on the subway tracks as the train was approaching. In fact, Sherlock had practically gotten himself thrown onto the tracks but had managed to escape with only a scratch on his cheek while the murderer had not been so lucky - after cuffing the killer, Sherlock had made sure to break his legs for good measure. In the aftermath of the chase, Sherlock and John had stood in the living room of their flat, faces glowing, bodies sweating, laughing breathlessly, oh-so-giddy. Sherlock had taken John by the hand and they had moved silently into his room. Then they were on his bed, and suddenly their lips were crashing together as they moaned with energy, passion, excitement, and lust. Sherlock's long fingers danced underneath John's jumper, John's weathered hands undid the buttons of Sherlock's shirt. Swollen, longing, aching lips teased against one another in laughter and happiness.

After that moment, it would forever be Sherlock and John, John and Sherlock.

Outside of the flat, though, Sherlock remained expressionless, his eyes glass-like, his lips and eyebrows forming a straight and unreadable line. To appear emotionless was power. To appear emotionless was the key to protection and security. Show where your heart lay and those who wanted to hurt you would use that information to your disadvantage. That was where Sherlock's brilliance outmatched Moriarty's, where the consulting criminal was weak and where the consulting detective was strong. The consulting criminal's passions were etched into every crevice of his face - his fears, his hatred, his vengeance, his hurt.

Sherlock had to appear emotionless because he knew now that there was a beast living in the deepest recesses of his heart; an animal that he had suppressed for so long, naively unaware of its existence. But that beast was watching - and if anything were to happen to John, it would unleash the full power of its savage fury.


	3. A Rude Awakening

_**Hi everyone, and let me start by saying thanks so much for your support and your awesome ideas. When I first decided to make this a multi-chapter piece, I had tons of ambition and no idea how challenging of a task it would be. It has definitely been anything but easy and I often find myself disappointed with what I do end up writing, so your support and encouragement means the world to me.**_

_**Secondly, my apologies - it has taken far longer than I had hoped to update this work. I recently welcomed a wonderful little puppy into my life and my time has been devoted to him. So thank you, thank you, thank you for your patience. You are wonderful beyond words! :)**_

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Khan's life was a massive, pathetic, pitiful failure. At eighteen, he attended university for one semester. During that time, he partied hard and flunked each of his classes, then promptly dropped out and vowed that he would never return to the world of academia again. From there, he remained unemployed for two years and spent his time sitting on his parent's couch, watching bad television. Finally, his parents threatened to kick him out of the house if he couldn't help pay for groceries - and so, more out of desperation than motivation, he took up a dead-end job at the nearby fast food joint.

On his thirty-fifth birthday, Khan decided to go to a bar. But he was not going to celebrate. Rather, he hoped to drink away the sorrow of being a middle-aged man who still lived with his parents and earned minimum wage. He found a secluded corner booth and spent the next couple of hours taking tequila shot after tequila shot; he enjoyed the way the alcohol burned his throat and blurred his vision, his reality, and his pain. He sat in the booth until numbness took ahold of his senses; until a warm bubbling found its way into his stomach and he became contented with his piteous place in the world; until he was told that the bar was closing and that he would have to leave. Even as he tripped his way back home, the numbness that permeated through his senses was enough to make him smile and actually appreciate the beautiful, clear, warm air.

As he stumbled through an alleyway, the melodious sounds of music disrupted the night. The music was familiar and Khan started laughing with nostalgia as the chorus of "Stayin' Alive" filled his ears. At the sound, he was thrown back to secondary school - a time when life was so much easier and there were no expectations. He closed his eyes and imagined himself back in his secondary school's old gymnasium, during one of their dances. A voice, light and airy, interrupted his thoughts.

"You like this song?"

Khan jumped at the sight of a short man with dark hair and playful midnight brown eyes. The short man walked up to Khan and stuck out his hand for a shake before speaking again. "Sorry, where are my manners? Let me introduce myself. Name's Jim. You like this song?"

Khan nodded and, when the man named Jim smiled and admitted that he liked the song too (that in fact it was his all time _favourite_ song), Khan felt his heart flutter at the thought that maybe he had found a kindred spirit.

"I…I used to dance to this song in secondary school. That was…that was a long time ago now. Things were…simpler back then," Khan admitted, sounding forlorn. His head buzzed uncontrollably and he longed for more alcohol to sustain his state of numbness.

Khan's newfound companion gave a look of understanding and pointed to a patch of grey hair on his head before saying, "Yeah…I hear you, man. I am getting older and it scares the shit out of me."

Khan smiled, feeling a connection with this stranger.

"So," the man named Jim continued, "you want to grab a beer? I know a bar that's open late. Just around the corner."

Khan nodded again, his eyes glowing eagerly at the thought of letting his senses tumble even further into oblivion.

The stranger's smile grew bigger. "Cool, let's go."

As they walked down the alleyway together, Khan found that a million questions were buzzing in his head - was his newfound companion just as lonely, just as pathetic, just as pitiful as Khan himself? But when Khan turned to look at Jim, he felt his heart turn fuzzy with apprehension. Jim's eyes were no longer warm, his smile no longer welcoming. He was watching Khan with a calculating expression. And despite the alcohol swirling through his system and slowing his senses, a red light began to flash in Khan's head - he had seen this man before. But where? He strained to draw memories from the black void that was currently his mind. And then the puzzle pieces came together - this man looked just like the criminal Jim Moriarty. The very same Jim Moriarty who had been in the news recently for serious crimes which included stealing the Crown Jewels and opening the vault at the Bank of England…and who had been shockingly acquitted.

A lump formed in Khan's throat and he found that he was having trouble swallowing. But as he decided that perhaps it was a better idea to just go home and sleep off his drunken state, Moriarty grabbed a syringe from a pocket and a brick from the alley floor. Next thing Khan knew, he was being stabbed with the syringe, hit over the head with the brick, and then his world was tumbling from numbness into complete shadow.

* * *

When Khan awoke, he could not remember anything about himself. In fact, he was no longer Khan. For one, the man that woke up looked different from Khan; this man was taller, more muscular, with darker hair, colder eyes, and sharper features. Secondly, this man felt different from Khan. He was indescribably weak, nauseous, trembling, and his body was heavy like a weight - it was as if he had been sleeping for around 300 years. But it was more than that - where Khan's mind had been filled with nothing but emptiness, self-pity, and self-loathing, this man's mind was spinning out of control with mounds and mounds of data - chemical equations, algebraic formulas, various languages.

Yet out of the mounds and mounds of data, there was one thought that rumbled louder than all the others: that of a particular John Watson, former army doctor. The man who had just awoken had no clue about his own identity, where he came from, or where he currently was - but he completely and fully understood John Watson. He knew how John looked - beautiful, dependable, and strong with grey-blonde hair, soft blue eyes, gentle lips, and faint but harsh wrinkles of experience outlining the skin. He knew the way John smelled - like fresh wool jumpers and springtime-scented laundry detergent. He knew the way John tasted - of black tea laced with spices and adventure. And he most certainly knew above all else that he was hopelessly, unbearably, and completely in love with John.

Suddenly, a sickening fear ricocheted through his weak body. Where _was_ John? He tried to force himself to sit upright but felt like he was moving through molasses. With a groan, he moved his head to the side to see if John was next to him, but he was greeted by nothing more than a metal wall. Moving his head to the other side, he was greeted by more metal and quickly came to the realization that he was lying in a slim metal tube which had recently been opened.

The fear crawled up his throat, burning his esophagus and filling his mouth with a sour, foul taste. He was going to be sick; he flailed and struggled to sit up again but his muscles felt like jelly. With a feeble cough, he dry heaved, his lungs filling with an aching pain and his heart shuddering against his chest. He struggled to find his voice, to call for John, but he found himself breathless and winded. Where was John, where was John, where was John? Fear continued to drown him and he broke into a sweat.

Then there was a body crouching over him and, for an instant, his heart filled with hope. Was it John? But his heart plunged furiously into his stomach when the figure's face came into focus - it was a harsh face, a cold face. And it certainly was not John's. This face had ice blue eyes that burned into the soul, stern lips that clearly bellowed orders, and a harsh, strong voice that ricocheted off the walls as it demanded, "What's your name, son?"

And oh but the poor man in the metal tube couldn't think, couldn't hear, couldn't see, he was so filled with an ache and longing for John. For even though he couldn't recall his own identity, he knew within his soul that John and he were joined at the hip - that wherever he went, John followed...so where was John now? He didn't like the look of the figure before him, but he needed help and so he took a deep, shuddering breath and braced himself. Then, with all the strength he could muster, he found his voice. He was meekly able to utter one word: "John…"

The figure looming over him nodded and the man in the tube felt relief wash over him - perhaps this stern-lipped man could help him find John after all. But these hopes were shattered as the figure stretched out a large, steady hand before saying, "Welcome to Starfleet, John."


End file.
